Process of eliminating impurities from gasoline



R. B. DAY

May 14, 1935.

PROCESS OF ELIMINATING IMPURITIES FROM GASOLINE Filed Feb. 21, 1931.

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j% g m Patented May 14, 1935 UNITED STATES PROCESS OF ELIMINATINGIMPURI'I'IES FROM GASOLINE Roland a. Day, Palos Verdes Estates, can, as-

signor to Universal Oil Products Company,

Chicago, 11]., a corporation of South Dakota" Application February21,1931, Serial No. 517,601

9 Claims.

This invention relates to a process for treating products of petroleumdistillation or pyrogenetic decomposition, as well as natural gasolinesfor the purpose of improving the same as to color, odor, doctor test,and other characteristics desirable in a commercial product.

The present invention constitutes an improvement over the invention setforth in my copending application, Serial'No. 488,112 filed Oct. 11,1930 in which is described a process for contacting light hydrocarbonvapors with hydrochloric acid.

' The method as carried out in accordance with this invention isparticularly concerned with the elimination of sulphur and gums fromgasoline by continuous treatment of the gasoline in the vapor phase withhydrochloric acid and other materials capable of effecting a removalofsulphur and a polymerization of other undesirable constituents wherebythese may be readily removed.

It has been more or less common to treat the V distilled or crackedvapors from hydrocarbon oils with metallic chloride for the purpose ofcausing the recombination of the constituents into lighter forms. Manydisadvantages have attended this type of process, however, and thesedisadvantages have been due in no small degree to the diilicultyexperienced in handlingthe metallic halide.

It has been discovered that a marked saving intime and expense can beaccomplished by contacting in the presence of hydrochloric acid andsteam, the gasoline or other light hydrocarbon in vapor phase with anaqueous solution of a chloride or oxide of a metal whose sulphides aresoluble in hydrochloric acid, holding in suspension or solution achloride or oxide of a metal whose sulphides are insoluble inhydrochloric acid. Examples of the metals forming soluble sulphides arezinc, aluminum, iron, and cadmium, while examples of those metalsforming insoluble sulphides are copper, mercury, silver, and nickel andcobalt, the latter two metals being very slightly soluble.

The zinc or other chloride in aqueous solution can be held liquid by theuse of a moderate amount of steam and the presence in the solution'ofthe chloride of another metal, such as copper, whose sulphide isinsoluble in hydrochloric acid makes possible the desired reduction insulphur content of the hydrocarbon. The solubility of the metalchlorides differs to a large ex tent. For instance, with copper, cuprouschloride is insoluble in water while cupric chloride is soluble. Thespecific weight of the zinc chloride or oxide solution permits thesolution to hold in suspension any of the other metal chlorides oroxides even though these other'metal chlorides or oxides be insoluble.

It has already been proposed to treat hydrocarbon vapors with metallicchlorides in a. liquidvapor contacting apparatus, adding steam tomaintain the halide in solution. In such a proc- "ess, however, acertain amount of the chloride hydrolyzes forming solid or semi-solidintermediate reaction products. For example, using zinc chloride, a.large percentage of the chloride hydrolyzes to form zinc oxychloride, asfollows:

Also, in the reaction of the zinc chloride with the oil, (where Rrepresents the reactive hydrocarbon radicles) the following hydrolysisoccurs:

In any event, a very large percentage of the zinc chloride is convertedto oxychloride of zinc which is a solid and forms emulsions with theheavy ends of the gasoline, the tars formed, and the remaining zincchloride solution. It is necessary, in order to recover the zincchloride for further use as a reagent, to take the zinc chloride sludgeas it leaves the bottom of the tower, and dilute it with water, whichreleases the tar and oil, which is skimmed from the top of the tank. Thezinc chloride with the finely divided zinc oxychloride is pumped througha suitable filter where the zinc oxychloride is removed and discardedwhile the solution of zinc chloride is reconcentrated to treatingstrength and pumped back into the tower.

In contrast to the foregoing, it is an object of this invention toeifect an eflicient reaction between metallic chloride and light crackedhydrocarbon products or distillates in a contacting apparatus withoutthe formation of solid intermediate products.

This invention consists broadly in contacting a light hydrocarbonfraction, such as gasoline with a solution of a chloride of a metal,such as zinc, whose sulphide is soluble in hydrochloric acid, thissolution holding in suspension or solution a. reactive compound, such asthe chloride or oxide, of a metal such as copper whose sulphide isinsoluble in hydrochloric acid. To the light hydrocarbon fraction isadded suflicient steam to effect solution of the zinc or other chlorideand maintain the solution at any desired concentration by control of thevapor pressure, and sufficient hydrochloric acid to keep the balance ofthe reactions on the acid side so that hydrolysis will be defeated andno accumulation of solid oxychloride will occur. Air or oxygen may alsobe added at a suitable point before or after entry of the hydrocarbonvapors into the contacting apparatus, as it is found that the oxygenexerts a beneficial effect in retarding the formation of undesirablesulphur compounds.

The invention may be more readily understood if reference is had to theaccompanying drawing, in which:

Fig. 1 represents diagrammatically an apparatus in which the presentinvention may be carried out;

Fig. 2 represents an enlarged view of one of the bubble-caps recommendedfor use, and indicated diagrammatically in the broken away portion ofFig. 1.

Referring to the drawing, i represents a treating unit of the bubble-captower type, the bubblecaps being preferably of the type shown anddescribed in my copending application, Serial No. 394,763, filedSeptember 24, 1929. This type of bubble-cap tower is illustrated in Fig.2, in which 2 represents a horizontal bubble-tray having a plurality ofopenings therein, each opening having its wall formed annularly as asingle piece 3, extending upwardly as a pipe. 4 is a primary baifiecovering the mouth of pipe 3 and spaced therefrom and having adownwardly flanged lower portion and a serrated lower edge. 5 representsa second baflle, annular in form, surrounding the primary bafileadjacent to its flanged portion and curved upwardly near its upper lipor edge, and 5 represents a cap for preventing splashing around theupper edge of the annular baflie. This construction has been found tofurnish an intimate vapor-liquid contact, the vapor passing downwardlyunder the serrated lower edge of baflie 4 where it is broken up intobubbles, the bubbles rising with liquid around interior of annularbattle 5.

6 represents an inlet pipe for gasoline or other light hydrocarbonvapors, introduced from any suitable source, such as a cracking stillfor example. This pipe is provided with valve 1 and leads into treatingunit I near the lower end thereof. Leading into pipe 8 at suitablepoints are branch pipe 8, for the admission of steam, whose flow iscontrolled by valve 9, pipe 8' for the admission of air, controlled byvalve 9, and branch pipe I0, for the admission of hydrochloric acid gasfrom any suitable source, the flow of this gas being regulated bymanipulating a valve ll. l2 represents a pipe leading into the upperpart of treating unit i for the admission of a solution of one of thechlorides of a metal, such as zinc, whose sulphides are soluble inhydrochloric acid, holding in suspension a chloride or oxide of a metalsuch as copper, whose sulphides are insoluble in hydrochloric acid, thispipe being provided with valve l3, and I4 represents a pipe leading fromthe bottom of treating unit I for the withdrawal of spent metalchloride, this withdrawal pipe being provided with valve l5. From thetop of treating unit I a pipe l6 leads to the bottom of a fractionatingtower l'l, this second unit being similar in construction to the firsttreating unit, but which is really a bubble-cap aoomea fractionatingapparatus formaking end-point gasoline. This tower is provided with anoutlet pipe i0 near the top thereof leading to condenser 99, and throughcondenser coil 20 to storage. An outlet pipe 2|, provided with valve 22,leads from the bottom of fractionating tower l! to conduct away heavyends or bottoms". Pipes it and I8 may be provided with valves if it isdesirable or necessary. A short pipe (not shown) provided. with acontrol valve may lead into the downgoing vertical portion of pipe l8,for the introduction of ammonia.

In the operation of the improved process as carried out in accordancewith the present invention, valve I3 is opened and an aqueous solutionof one of the chlorides of a metal, such as zinc, whose sulphides aresoluble in hydrochloric acid, holding in suspension a chloride or oxideof a metal, such as copper, whose sulphides are insoluble inhydrochloric acid, enters pipe I! and builds up on the trays inside theunit and commences to overflow from one tray to the next; Valves 1, 9,II and 9', in case it is desired to use air, are opened to the requiredextent and gasoline vapors, steam, and air begin to flow upwardly, andcontact with the downflowing liquid contacting agent on the bubbletrays. A prolonged and efficient contact is thus secured, thehydrochloric acid gas reacting with the hydrocarbon over the contactingagent. Sufilcient hydrochloric acid gas is added to the inflowinghydrocarbon vapors so that the hydrochloric acid will immediatelydecompose any oxy-compounds formed from the liquid contacting agent asfast as formed. For instance, in the case of zinc chloride, any zincoxychloride would be decomposed as follows:-

As long as the balance is maintained on the acid side of the equation bythe addition of sufficient hydrochloric acid, no accumulation of thesolid will occur. Sludge will accumulate at the bottom of treating unitI and may be drawn of! through pipe M by opening valve l5, but thissludge will contain only the tars and heavy polymers which can be easilyremoved without filtration. No zinc chloride is used up, and this factconstitutes a marked saving in expense, as zinc chloride costs about$0.05 per pound against $0.008 per pound as the cost of hydrochloricacid. A marked saving in time is also effected by enabling the refineryoperators to dispense with the laborious operation of filtration. Enoughsteam is admitted through pipe 8 to maintain the metallic chloride insolution at any desired concentration. In practice a steam content byliquid volume of 15% will give a zinc chloride concentration of aboutBaum, a 10% content, a concentration of 80 Baum, and so on. The treatedgasoline or other hydrocarbon vapors leaving treating unit I by pipe l6pass into fractionating tower I! where they are rectified to end-pointgasoline, the bottom being removed by pipe 2|. The lighter fractionsfrom tower I! are conducted by pipe l8 through condenser 20 surroundedby water jacket i9, where they are condensed and the condensateconducted to storage. Ammonia may be introduced through pipe 48 toneutralize any hydrochloric acid coming over with the vapors.

If air is introduced along with the steam and hydrocarbon vapors, itsrate of supply must be carefully controlled, since an excess of air willtend to injure the color of the finished gasoline.

ltn case the metal oxides are used instead of the chlorides, theaddition of air is unnecessary, because the oxygen liberated from theoxides will act to decompose the sulphides formed.

I claim:

1. A process for refining hydrocarbon vapors which comprises addinghydrogen chloride and steam to the vapors, and contacting the vapors inthe presence of the added hydrogen chloride and steam with an aqueoussolution oi a water soluble chloride of a metal whose sulphide issubstantially soluble in hydrochloric acid, said solution containing areactive compound having the character and action of the chlorides andoxides oi the metals whose sulphides are substantially insoluble inhydrochloric acid.

2. A process for refining hydrocarbon vapors which comprises addinghydrogen chloride and steam to the vapors, and contacting the vapors.

in the presence oi! the added hydrogen chloride and steam with anaqueous solution of zinc chloride containing a reactive compoundhavingthe character and action of the chlorides and oxides of the metals whosesulphides are substantially insoluble in hydrochloric acid.

3. A process for refining hydrocarbon vapors which comprises addinghydrogen chloride and steam to the vapors, and contacting the vapors inthe presence of the added hydrogen chloride and steam with an aqueoussolution of a water soluble chloride of a metal whose sulphide issubstantially soluble in hydrochloric acid, said solution containing achloride of a metal whose sulphide is substantially insoluble inhydrochloric acid.

4. A processfor refining hydrocarbon vapors which comprises addinghydrogen chloride and steam to the vapors, and contacting the vapors inthe presence of the added hydrogen chloride and steam with an aqueoussolution oi! a water soluble chloride of a metal whose sulphide issubstantially soluble in hydrochloric acid, said solution containing anoxide of a metal whose sulphiige is substantially insoluble inhydrochloric ac 5. A process for refining hydrocarbon vapors whichcomprises adding hydrogen chloride and steam to the vapors, andcontacting the vapors in the presence of the added hydrogen chloride andsteam with an aqueous solution oi! zinc chloride containing a chlorideof a metal whose sulphide is substantially insoluble in hydrochloricacid.

6. A process for refining hydrocarbon vapors which comprises addinghydrogen chloride and steam to the vapors, and contacting the vapors inthe presence of the added hydrogen chloride and steam with an aqueoussolution of zinc chloride containing an oxide of a metal whose sulphideis substantially insoluble in hydrochloric acid.

7. A process for refining hydrocarbon vapors which comprises addinghydrogen chloride and steam to the vapors, and contacting the vapors inthe presence of the added hydrogen chloride and steam with an aqueoussolution of zinc chloride containing copper chloride.

8. A process for refining hydrocarbon vapors which comprises addinghydrogen chloride and steam to the vapors, and contacting the vapors inthe presence of the added hydrogen chloride and steam with an aqueoussolution of zinc chloride containing copper oxide.

9. A process for refining hydrocarbon vapors which comprises addinghydrogen chloride and steam to the vapors, and contacting the vapors inthe presence of the added hydrogen chloride and steam with an aqueoussolution of a water soluble chloride of a metal whose sulphide issubstantially soluble in hydrochloric acid, said solution containing areactive compound selected from the group consisting of the chloridesand oxides oi metals whose sulphides are substantially insoluble inhydrochloric acid.

ROLAND B. DAY.

